Methods and apparatus for induction heating



Jan. 6, 1959 D. M. CRISWELL METHODS AND APPARATUS FOR INDUCTION HEATING Filed March 14, 1957 FIG.- 2

C II V vv INVENTOR DICK M. CRISWELL h mgm M.

" i nite NETHGDS AND APPARATUS FDR HNDUCHQN HEATING Dick M. Criswell, Wheeling, W. Va, assignor to Wheeh ing Steel (Iorporation, a corporation of Delaware Application March 14, 1957, Serial No. 645,951

4 Claims. (Cl. 219-40413) This invention relates to methods and apparatus for induction heating and particularly to methods and apparatus for induction heating of fiat and irregular surfaces by high frequency current, 6. g., annealing, hot extrusion or spot heating. Prior to the present invention, no

satisfactory method of progressively heating a flat or or annealing and is particularly suited for spot heating and extrusion.

I provide an inductor having at least two separable members forming a treating zone, separable connections between the members whereby the members may act as a single inductor and means supplying current to said members. Preferably, the separablemembers each contain a group of induction coils, cylindrical, square, flat or any desired shape, each fitted for coolant circulation. Preferably, the connections between the members are separable mechanical contactors such as matched male and female members.

Other purposes, advantages and objects of the present invention will be apparent from a consideration of the following description of a preferred embodiment of the invention and the accompanying drawings in which:

Figure 1 shows diagrammatically a preferred electrical circuit for two spot flat surface heating;

Figure 2 shows a top plan view of a work piece in an apparatus for heating according to this invention; and

Figure 3 is a section on the line III-Ill of Figure 2.

Referring to the drawings, I have illustrated an upper conductor member having a depending V-shaped elec-' trode 11 at each end. A bottom conductor member 12 is provided with V-shaped slots 13 at each end adapted to receive and contact the electrode members 11 on the upper conductor member 10. The upper conductor memher is provided with spaced openings 15 and 16 carrying multi-turn inductor coils 17 and 18, respectively. Each of the coils 17 and 18 are hollow and are connected to passageways 19, 20 and 21 in the conductor 10 through which water is passed to cool the conductor member 10 and the inductor coils 17 and 18. The lower conductor member 12 is provided with an opening 22 positioned in line with opening 15 of the upper conductor 10 carrying a multi-turn inductor coil 23. The coil 23 is hollow and connected to passageways 24 in the conductor member 12 through which water is circulated for cooling the conductor member 12 and coil 23.

An upper heat-resisting insulating element 25 is placed between the work 26 to be treated and the upper conductor member 10. This heat-resisting element 25 may States Patent be of Transite or similar material. A similar lower heat resisting element 27 is placed between the work 26 and the lower conductor member 12.

Current from a high frequency generator (not shown), preferably in the range 3,000 to 10,000 cycles, is connected to one arm 12a of the lower conductor member 12. Current flows through the conductor member 12 through the coil 23 to the V groove slots 13. The current then flows from the V groove slots 13 to the V-shaped electrodes N and into the upper conductor 10, through the coils 17 and 18 to the opposite electrode 11; thence to the V-groove slot 13 the lower conductor member 12 and the second arm 12b of the lower conductor member.

The coils 17 and 23 heat by induction a spot on the work between them for annealing or forming. Similarly the coil 18 heats by induction a separate and spaced spot on the work. When heating is completed the conductor members 10-and 12 are simply pulled apart, the work is passed out and a new work piece introduced. The coils are then brought together and the coils 17, 23 and 18 begin induction heating of the new work piece.

While I have illustrated and described a present preferred embodiment of my invention, it will be understood that the invention may be otherwise embodied within the scope of the following claims.

I claim:

1. An inductor for heating flat or irregular shapes comprising at least two separable members forming therebetween a treating zone, openings in at least one of said memers corresponding to the areas to be treated, inductor means in said openings, interengaging electrode members adapted to connect the members and the inductor means in series and means supplying current to the members.

2. An inductor for heating flat or irregular shapes comprising at least two separable members forming therebetween a treating zone, openings in said members corresponding to the areas to be treated, hollow inductor means in said openings, passage in the members forming a continuous passage with the interior of the hollow inductor means, means supplying coolant to said passages, interengaging electrode members on the separable members and the inductor means adapted to connect the members in series and means supplying current to the members.

3. An inductor for heating flat or irregular shapes comprising at least two parallel plane members, forming therebetween a treating zone, openings in at least one of said members corresponding to the areas to be treated, inductor means in said openings, interengaging electrode members along two opposite sides of said members adapted to separably connect the members and theircorresponding inductor means in series and means supplying current to the members.

4. An inductor for heating flat or irregular shapes comprising at least two parallel plane members, forming therebetween a treating zone, openings in at least one of said members corresponding to the areas to be treated, inductor means in said openings, a V notch along each of two opposite sides of one of said members, a mating V projection along each of two corresponding opposite sides of the other member, said V notch and l projection forming a separable connection between the members, and means supplying current to the members.

References ited in the file of this patent UNITED STATES PATENTS 

